The present invention relates to systems and methods for improving the linearity of an analog transmission, and more particularly to a system and method in which a power series correction is applied to a transmission received on a fiber optic cable to reduce non-linearities in the received transmission.
The use of fiber optic systems is increasing, in part because fiber optic cables are able to provide the bandwidth needed for transmission of a multiplicity of information signals. The information signals may be digital or analog, with analog signals being preferred in many applications because of the relatively lower costs and lower power requirements of analog equipment. However, as is known, analog systems may introduce non-linearities into the received transmission because of the high transmission amplification levels that are typically needed to assure reception of the transmission with sufficient strength. The non-linearities cause distortions that may be manifested as crosstalk in multichannel systems that has heretofore been difficult to remove from the received transmission.
Multichannel fiber optic systems carry information signals in channels that are separated from one another by non-information bearing portions, denoted guard bands. An example of a multichannel fiber optic system is one in which the transmissions are frequency division multiplexed.
It is an object of the present invention to provide a novel method and system for improving the linearity of an analog transmission that obviates the problems of the prior art.
It is another object of the present invention to provide a novel method and system for improving the linearity of an analog transmission in which a power series correction is applied to a received transmission.
It is yet another object of the present invention to provide a novel method and system for improving the linearity of an analog transmission in which the energy of a non-information bearing portion of a received transmission is measured and provided as a power series correction to a received transmission.
It is still another object of the present invention to provide a novel method and system for improving the linearity of an analog transmission in which a notch filter reduces the energy in a guard band between channels in a multichannel fiber optic transmission system and in which the energy of the notch-filtered portion of a received transmission is measured and provided as a power series correction to an information signal in a received transmission.
It is a further object of the present invention to provide a novel method and system for improving the linearity of an analog transmission in which the energy in a guard band between channels in a multichannel fiber optic transmission system is measured and in which an inversion of a power series representation of the measured energy is a linearity correction for a received transmission.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the preferred embodiments.